Nanoporous alumino- and borosilicate-mediated Meinwald rearrangement of epoxides
作者:Thomas E. Davies、Simon A. Kondrat、Ewa Nowicka、Joseline L. Kean、Christopher M. Harris、Joseph M. Socci、David C. Apperley、Stuart H. Taylor、Andrew E. Graham
DOI:10.1016/j.apcata.2014.12.031
日期:2015.3
Nanoporous alumino- and borosilicate materials, produced using an evaporation-induced self-assembly approach (EISA), efficiently catalyse the Meinwald rearrangement of epoxides in dimethyl carbonate (DMC) to produce the corresponding carbonylcompounds in high yield and excellent selectivity.
A functionalized Ti-containing polyhedral oligomeric silsesquioxane was anchored on the surface of an ordered SBA-15 and a non-ordered amorphous mesoporous silica. The physico-chemical characterization of the textural, thermal and electronic properties of the final anchored materials led to the evaluation of the distribution of Ti-POSS moieties on the silica surface, of the oxidation state and of the coordination geometry of the titanium centres. It was discovered that Ti-POSS are accommodated mainly as dinuclear dimeric species on the external surface of ordered mesoporous silica or in the large mesopores of non-ordered silica supports.Epoxidation tests on unsaturated terpenes (limonene, carveol and a-pinene) with TBHP as oxidant were performed to monitor the activity and accessibility of Ti(IV) sites in the anchored samples and compared with conventional titanocene-grafted Ti/SBA-15 and Ti/SiO2 systems.The different chemoselectivity recorded over anchored catalysts, with respect to the grafted ones, can be a potential diagnostic tool to shed light on the mechanism or the molecular intermediates occurring at the surface during the oxidation reaction. (C) 2011 Elsevier B.V. All rights reserved.
The Baeyer-Villiger reaction of pinanones (bicyclo[3.1.1]heptanones)
作者:Alan F. Thomas、Florence Rey
DOI:10.1016/s0040-4020(01)88515-x
日期:1992.1
The Baeyer-Villiger reaction of bicyclo[3.1.1]heptanones yields the expected lactones, but with some difficulty. These lactones readily react with alcohols, including the ethanol present in commercial chloroform, to give the corresponding hydroxy esters. Pinocamphone and isopinocamphone exhibit conformational control in the Baeyer-Villiger reaction, the trans-isomer yielding mainly the expected lactone
Preparation, Characterisation and Reactivity of Neutral Mono‐η
<sup>4</sup>
‐oxadiene Complexes of Molybdenum and Tungsten Containing Bidentate Donor Ligands
作者:Thomas Schmidt、Frank Bienewald、Richard Goddard
DOI:10.1002/cber.19961290310
日期:1996.3
Neutral molybdenum and tungstencomplexes containing only one η4-coordinated 1-oxa-1,3-diene ligand are obtained diastereospecifically from the reaction of the corresponding dicarbonylbis(oxadiene) complexes with bidentate donor ligands capable of forming five-membered ring chelates. Thus, dicarbonylbis[η4-(R)-(+)-pinocarvone]metal complexes react with 1,2-bis(dimethylphosphanyl)ethane (dmpe) or N